 var num = 0;
 var scrollFunc = function(e) {
     ee = e || window.event;
     if (e.wheelDelta) { //IE/Opera/Chrome  
         // console.log(e.wheelDelta);
         if (e.wheelDelta == -120) {
             //向下
             if (6 == num) {
                 num = 6;
             } else {
                 num++;
                 $(document).scrollTop((window.innerHeight * (num / 2)));
             }
         } else {
             // 向上
             if (0 == num) {
                 num = 0;
             } else {
                 num--;
                 $(document).scrollTop((window.innerHeight * (num / 2)));
             }
         }
     } else if (e.detail) { //Firefox  
         console.log(e.detail);
     }
 }

 /*注册事件*/
 if (document.addEventListener) {
     document.addEventListener('DOMMouseScroll', scrollFunc, false);
 } //W3C  
 window.onmousewheel = document.onmousewheel = scrollFunc; //IE/Opera/Chrome/Safari